The total cost of the conversion needs to be depreciated and can be entered as a separate asset from the house which also needs to be listed as an asset.
The rest of the furniture/supplies could be depreciated or expensed depending on the total costs of each item.
But since this B&B was not put into service until 2021 nothing is reported on the 2020 return. You have a year to either read up on rules of being a landlord and/or seek local professional assistance to set up your books or file the first Sch E. https://www.irs.gov/pub/irs-pdf/p527.pdf
